Apoptosis inhibitors and regenerative nanomedicines
Senescence can be considered a stress response intensified by genomic
damages, nucleotide mutations, telomere attrition, protein aggregation
or misfolding, and oxidative damage causing or initiating the
age-related diseases. Moreover, senescent cells can participate in the
induction of pro-inflammatory phenotype
(Campisi, 2013;
Childs, Durik, Baker, & Van Deursen,
2015; McHugh & Gil, 2018;
Muñoz-Espín et al., 2013;
Serrano, 2014). The production of
pro-inflammatory agents and suppression of cell proliferation are two
important hallmarks of senescence response that alter the intracellular
and intercellular communications (Childs
et al., 2015). The findings have shown a complex correlation between
senescent cells, apoptosis, and mitochondrial malfunction with increased
age (Sun et al., 2016). Studies on mice
and human models have confirmed the accumulation of the senescence
biomarkers in tissues, which are associated particularly with
atherosclerosis, cancer, rheumatoid arthritis (RA), and
neurodegenerative disorders (Campisi,
Andersen, Kapahi, & Melov, 2011;
Erusalimsky & Kurz, 2005;
Krizhanovsky et al., 2008).
Nanomaterials can be functionalized with ligands, immunoglobulins, or
polymers for selective targeting of senescent cells which can be used
for therapeutic purposes in addition to diagnostic applications.
Besides, the capability of the nanomaterials in detection of cancer
cells or induction of apoptosis, some nanomaterials are known in
regenerative medicine. Moreover, they can have a determinant role in the
restoration of aged, disturbed, damaged, or even lost cells resembling
their original structure and function. Additionally, these materials can
have the extra potential to diminish the disadvantageous phenotype of
the aged cell by modulating the senescence-associated secretory
phenotype (SASP) (Salminen, Kauppinen, &
Kaarniranta). They can maintain tissue-associated functions with
encapsulated inhibitors, small molecules, and effectors, or by
reprogramming these cells (Muñoz-Espín,
2019). The progress in nanotechnologies and nanomedicines to treat the
senescent cells as anti-aging agents is however still in its infancy,
and since the toxicity of many of them has been proven, the important
limitation in their application is accompanied by the concern of their
safety for human and environment. Some of the nano-compounds that are
shown effectivity in inhibiting apoptosis or cells regenerating are
listed in Table 5 .